Furnace regulation



July 3, c H. SMOOT FURNACE REGULATION Filed Sept. 26, 1950 2Sheets-Sheet l I l l l L r II 0 0 M M a m 8 Wm cT W 4 i A 1? B. Q m

July 3, 1934. c. H. SMOOT FURNACE REGULATION Filed Sept. 26, 1930 2Sheets-Sheet 2 M We Tm NS fl a i C ATTORN EYS Patented July 3, 1934 1UNITED STATES r 1,964,774 I FURNACE uncommon Charles H. Smoot,MaplewomLN. J.; Katherine Smoot, executrix of said Charles H. Smoot,de-, ceased, assignor to Katherine Smoot Application September 26, 1930,Serial No. 484,685 8 Claims. (Cl. 158-1) My present invention relates tofurnace regulation and comprises a method of remote control of thesupplies of fuel and air to a furnace to maintain any desired atmospherein the furnace,

5 whether oxidizing or reducing, and includes apparatus adapted to carryout the method. My invention is particularly concerned with the controlof the fuel and air to furnaces burning more than one kind of fuelandwhen applied to such type of furnace involves the division of the airsupply into a plurality of flows corresponding to the number ofdifferent fuels utilized and the control of each air flow in any desiredratio to the rate of supply of one of the fuels; the proportion--' ingof the fuels to the separate air flows being controllable from a centralpoint in the plant to obtain the desired atmosphere in the furnace orfurnaces.

' For a better understanding of my invention,

0 reference may be had to the accompanying drawings of which,-

Fig. 1 illustrates one embodiment of the invention applied to theregulation of a furnace burning both oil and coke oven gas; and x 5 Fig.2 illustrates another embodiment of the invention as applied to afurnace burning blast furnace gas and gas produced in a gas producerassociated with the furnace.

Referring to Fig. l, a furnace 1, shown specifi- 0 cally as an openhearth furnace, is supplied with fuel oil through a conduit 2 connectedto the burners 3 and 3 by means of branch conduits 4 and 4' and withcoke oven gas through a main 5 and branch pipes 6 and 6' connected with5 the burners 3 and 3 respectively. Regulating valves 2a and 5a in theconduit 2 and main 5 respectively control the fuel supplies to thefurnace 1. Steam under pressure for atomizing the fuel oil is suppliedthrough a pipe '7 provided with a regulating valve 7a and connected bymeans of branch pipes 8 and 8' with the branch conduits 4 and 4'respectively. Air is supplied to the furnace from a blower 9 through aconduit 10 con nected to the checker brick passages 11 and 11' by meansof conduits 12 and 12', respectively.

Suitable valves in the branch conduits for the fuel, steam and airareprovided, as usual, for reversing the dirction of flow through thefurnace. According to the invention, the air supply is divided into twoportions corresponding to the number of fuels employed and the volume ofair flow of one portion is maintained in proportion to the flow of oilto the furnace and that of the other portion is maintained in proportionto the flow of coke oven gas to the furnace.

damper 13a to maintain a fixed relation between In the particularembodiment illustrated the division of the air supply is effected bydividing the air inlet to the blower 9 into two channels 13 and 14 inwhich are located the dampers 13a and 14a respectively controlled bymeans now to be described. These means comprise a master controller 15,air regulators 16 and 1'? associated respectively with the dampers 13aand 14a, and regulators 18, 19 and 20 associated respectively withregulating valves 2a, 5a and To.

Each of the various regulators above enumerated is diagrammaticallyillustrated for simplicity as comprising a balancing lever arranged fordirect control of the associated damper or valve in response to forcesvarying as a function of the element controlled and in response to aforce transmitted to the lever by the master controller. Preferablythese regulators would be of the antihunting balanced type employingauxiliary power fluid for operating the controlled elements. As suchregulators are now well known in the art it is not believed necessary toillustrate or describe the same in detail. For example these regulatorsmay take the form illustrated in Fig. 2 of my Reissue Patent No. 16,507,dated December 21, 1926. Regulator 16 is arranged to be responsive tothe suction in channel 13 in advance of the damper 13a and to a mastercontrol force transmitted through a pipe 21. RegulatorlG operates thethe force transmitted through pipe 21 and the differential pressurebetween that of the atmosphere and the suction in channel 13, whichdifferential is a measure of the volume of air flowing through thechannel. Similarly regulator 17 is arranged to operate damper 14a toaintain a fixed relation between a master force transmitted; through apipe 22 to the balance lever of the regulator and the volume of airflowing through the channel 14as measured by the dif-' ferentialpressure between the atmosphere and the suction in advance of the damper14a. Regulator 18 is arranged to control valve 2a to maintain apredetermined relation between a master force transmitted through a pipe23 to the balance lever of the regulator and the volume of fuel oilflowing through the main 2 'as measured by the differential in pressureacross an orifice 24 in the main 2. Similarly regulator 19 is arrangedto control damper 5a, to maintain a predetermined relation between amaster force transmitted through pipe 25 and the volume of coke oven gasas measured by the pressure differential across a constriction 26 in thegas main 5. Regulator 20 is arranged to control the steam valve 7a tomaintain a predetermined relation between a master force transmittedthrough pipe 27 and the pressure of the steam at a point between thevalve 7a and the burners 3 and 3'.

The master controller 15, while constructed along the same generalprinciples as the master controllers heretofore disclosed in various ofmy prior applications and patents and shown best,

perhaps, in the .reissue patent above referred to,"

comprises an improved structure particularly arranged to permit theready control of the atmosphere of the furnace and to provide means forrapid change thereof from oxidizing to reducing or Vice versa. In theimproved construction illustrated, the controller includes a mainchamber28 to which fluid under pressure is supplied from any suitablesource (not shown):- through a pipe 29 provided with a restrictedorifice 0, and auxiliary chambers 31, 32, 33 and 34. Th pressure of thefiuid in chamber 28 is maintained at any desired value by means of a cupvalve 35 normally permitting a slight leakage of fluid from the chamber.A pivoted lever 36 carries cup valve 35 atone end and is connected atits other endto one end of a spring 3'1 the tension of which isadjustable by means of a handoperated gear 38 meshing with a rack 39attached to the lower end of the spring.

For each setting of the hand 'gear 38, valve 35 will thus maintain apredetermined pressure in chamber 28, which pressure will be such thatthe downward force thereof acting upon valve 35 will just equalize uponlever 36 the effect of theten- -sion of spring 3'7. Fluid under pressurepasses from chamber 28 into auxiliary chambers 31, 32, 33 and 34 by wayof pipes 40, 41, 42and 43 respectively and bleeds from these auxiliarychambers to the atmosphere through pairs of valve controlled orificesindicated in the drawings by .the reference numerals 44 and 45; chambers31 1 diate one pair of orifices 44 and 45 associated with chamber 32depending upon the position of a throw-over valve 46 to which areconnected branch pipes 47 and 48. Similarly pipe 22 may be connectedwith either chamber 31 or 32 intermediate the other pair of orifices 44and 45 associated with these chambers by manipulation 55.

of a throw-over valve 49 to which are connected branch pipes 50 and 51.Pipes 23, 21 and 27 may be connected with either of chambers 33 or 34 bysuitable manipulation of throw-over valves 52, 53 or. 54 to which pairsof branch pipes 55 56, 5758,- and 59-'-60 are respectively con nected.Preferably valves 46 and 49 are arranged, as shown, for joint operation,as are valves 52,

53 and 54. The various branch connections to the master controller, incombination with the throw-over valves, and pairs of manually ad-;

justable leakage ports 44 and 45 permit of the widest possibleflexibility of the system. It willbe noted that the pressures inchambers 31, 32, 33 and 34 will be less than that 'in chamber 28 andthat each may be independently. adjusted by means of the valves in theconnecting pipes 40, 41, 42 and 43 respectively. 'With the throw-overvalves in the position shown, that is, with pipes 25 and 22 connected tochamber 31 and with pipes 23, 21 and 27rconnected to chamber 33, the

relative proportion of coke oven gas to fuel oil is adjusted bymanipulation of the valve in pipes 40 and 42. The valves controlling theports- 44 and 45 associated with branch pipes 4'7 and 50 are thenadjusted for the desired ratio of gas to air for the furnace atmospheredesired and similarly the'valves controlling'the ports 44 and 45associated with branch pipes 55, 57 and 59 are adjusted for the ratio offuel oil to air and for the preferred "atomizing steam pressure.Assuming that the above adjustments have been made with a view ofmaintaining an oxidizing atmosphere in the furnace, then the valvescontrolling the leakage ports 44 and 45 associated with chambers 32 and34 may be adjusted for such proportions of fuel to air as will give areducing atmosphere in the furnace, while the relative proportions ofgas to fuel oil may be kept the same as before or adjusted to a newvalue by the valvesin pipes 41 and 43. With the improved mastercontroller above described and with the divided air supplies to thefurnace, it will be apparent that an operator can vary the relativeamounts of the two fuels employed or may vary the furnace rating withoutupsetting the proportions of air to fuel as previously adjusted and thathe may, without readjustment, readily shift from one set of fuel airproportions to a second by simple manipulation of throw-over valves.

In operation should it be desired to increase the furnace rating, it isonly necessary for the operator to manipulate gear 38 in a direction toincrease the tension of spring 37 and to thereby cause an increase inpressure in chamber 28 .with corresponding proportionate increases inpressures in all the auxiliary chambers and in the master lines 25, 22,23, 21 and 27. 'The increased pressures in these lines upsets thebalance of each of the regulators associated therewithaand causesoperation thereof to increase the gas and oil flows proportionately tothe increased master pressures and to open the dampers 13a. and 14a. andthe steam valve 7a to correv spondingly increase the air flows and thesteam pressure. Conversely, operation of the gear 38 in a direction toreduce the tension of spring 37 causes proportionate reduction of eachof the fuel, air and steam supplies.

In combination with the apparatus above described, means are preferablyprovided for maintaining the pressure in the furnace chamber equal tothat of the atmosphere irrespective of the furnace rating or of theproportions of fuel to air. These means may comprise a regulator, suchas 61, responsive to the pressure within the furnace and to a constantforce, such as the weight 62, arranged to control ,a damper 63 in thestack 64 of a waste heat boiler 65 associated with the open hearthfurnace 1. Alternatively, the regulator 61 could be arranged to directlycontrol a damper or exhauster in the conduit 66 through which the wastegases are withdrawn from the furnace.

In Fig. 2, I have illustrated a control system substantially similar tothat above described with reference to Fig. 1 but'applied to the jointcontrol of a gas producer and a furnace burning a mixture of the gasproduced in the producer and blast furnace gas. As in Fig. 1, thecontrol system includes a master controller arranged to con-' In Fig. 2,an open hearth reversing furnace is designated by the reference numeral67 and is shown as including gas and air checker brick passages 68, 68'and 69, 69 respectively leading 5 to burners (not shown) within thefurnace chamber 70. A gas producer 71 supplies gas to a conduit 72connected through suitable reversing valves with either checker brick.passage 68 or 68'. Blast furnace gas supplied through a conduit 73 ismixed with the gas from the producer in conduit '72 and suppliedtherewith to the furnace. A blower 74 delivers air to the furnacethrough a conduit connected through suitable reversing valves withpassages 69 and 69'. As in the system disclosed in Fig. l the air supplyis divided into two parts, each separately controllable and eachmaintained in proportion to the flow of one of the fuels supplied to thefurnace. The division of the air supply in the regulating system nowunder discussion comprises a partition 76 within the conduit '75arranged to cause the air from blower 74 to pass in two parallel streamsduring at least a part of its travel through conduit 75. Dampers 77 and78 are provided for independent adjustment of the two air streams undercontrol of regulators 79 and 80 respectively; Regulator '79 isresponsive to a master pressure transmitted through a pipe 81 and to thevolume of air passing damper '77 as measured by a pressure differentialtaken for example from the maximum and minimum pressure points of ashort Venturi section 82 inserted in this stream; regulator '79operating to maintain a predetermined relation between the masterpressure in pipe 81 and the volume of air passing damper '77. Similarlyregulator 80 is arranged to control damper '78 to maintain apredetermined relation between a master pressure transmitted through apipe 83 and the, volume of air passing damper 78, as measured by thepressure differential between the maximum and minimum pressure points ofa Venturi section 84 located in the stream of air passing damper 78. 1,r

The fuel control to the furnace comprises a regulator 85 which adjusts adamper 86 in the conduit 73 to maintain a predetermined relation betweena master pressure transmitted through a pipe 8'7 and the volume of blastfurnace gas as measured by pipes 88 and 89 connected to pipe 73 ateither side of a constriction 90 and a regulator 91 arranged to controlthe flow of air through a conduit 92 to the gas producer '71 and tocontrol, therefore, the volume of producer gas generated therein andflowing to the furnace. Regulator 91, responsive to a master pressuretransmitted through a pipe 93 and to .the volume of air flowing throughconduit 92 as measured by the differential in pressure across a 1construction 94in the conduit 92, adjusts a valve 95 in a pipe 96conveying steam to the producer ulating the feed of fuelto the gasproducer 71- and the pressure of the gases in the furnace chamber 70 ofthe open hearth furnace 67. These -means.comprise-th e regulators97 and98; the

former-of which varies electrical resistance in the circuit of a motor99 driving the fuel feeder 100 of the producerinresponse to a masterforce transmitted through a pipe 101, and to the speed of the motor 99and the latter of which controls a damper 102 in the stack 103 of thefurnace 67 in response to 'the pressure in the chamber 70 as measured bya pipe 104.

The master controller 105, controlling the regulators 79, 80, 85, 91 and9'7, is substantially similar to that disclosed in Fig. 1. It comprisesthe main chamber106 in which the pressurejis manually adjustableby thehand gear 107 controlling the-opposing force applied to cup valve 108,and three auxiliary chambers9l09, 110 and 111 in communication with themain chamber by means of the throttled. connecting pipes 112, 113 and114 respectively. Fluid under pressure supplied through a pipe 115 tochamber 106 bleeds from each of chambers 109 and 110 through three pairof valve controlled orifices 116-- -11'7 andfrom chamber 111 through twopair of valve controlled orifices 116-117. Pipes 93 and 87 are connectedto chambers 109 and 110 respectively intermediate one pair of orifices116'-117 and pipes 81 and 83 are adapted to be connected intermediateeither of the other two pair of orifices associated with chambers 109and 110 respectively by manipulation of throw-over valves 118 and 119respectively; valve 118 being connected to chamber 109 by means ofbranch pipes 120 and 121 and valve 119 being connected tochamber. 110.bymeans of branch pipes 122 and 123. Preferably valves 118 and 119 arelinked together, as shown, to permit joint operation thereof by theoperator.

Pipe 101, leading to the fuel regulator for the gas producer isconnected to chamber 111 intermediate one pair of orifices 117-118 and apressure gauge 124 is connected to this chamber intermediate the otherpair of orifices. Obv'ously additional gauges could be provided ifdesired, to indicate to the operator the various master forces and toguide him in their adjustment.

The operation of the apparatus of Fig. 2 will becomparatively clear fromthe above description and from that already given in connection valvescontrolling the leakage ports 116117 as-.

sociated with branch pipes 120 and 122 are adjusted for such volumes ofair compared with the respective gases as will maintain an oxidizingatmosphere in the furnace and the valves controlling the leakage ports116117 associated with branch pipes 121 and 123 are adjusted for suchvolumes of air compared with the respective gases aswill maintain areducing atmosphere in the furnace. Shifting'of the throw-over valves118 and 119 from the position shown to connect pipes 81 and 83 withbranch pipes 121 and 123 respectively thus causes operation of theregulators '79 and'80 in a direction to close dampers 377 and '78 toreduce the air supplied to the furnace 70 relative to the fuel supply. Areturn of valves 118 and 119 to the position shown in the drawings,restores the pressures in pipes 81 and 83 to their respectiveformer'valves. and causes operation of regulators ;79 and 80 to increasethe air flows to the furnace'by opening of dampers- 7'7 and T8 and tothereby restore oxidizing conditions within the furnace.

;Should it be desired to increase the supply of blast furnace gasrelative to that of the gas from sure fluid therethrough. This theproducer, it is only necessary to manipulate the valve in pipe 113 toincrease the flow of presincreases. the pressure in chamber 110 andtherefore the pressures in pipes 83 and 87 as well, thus simultaneouslyand proportionately increasing the flow of blast furnace gas and thatportion of the air supply which is correlated therewith.

Normally the feed of fuel to the gas producerneed not be varied in exactcorrespondence with the air supply thereto; it being sufficient for mostpurposes to maintain the fuel feed at a,;constant rate. Adjustment ofthe valves controlling leakage ports 116117 associated with pipe 101 iseffective however to cause regulator 97 to vary the fuel feed wheneverdesired, and the arrangement at the master is such that adjustment of 7hand gear 107 to vary the total ratingof the furnace willproportionately-vary the fuel feed to the producer. Should closercorrespondence between the fuel and air supplied to the producer bedesired, it is only 'necessaryto so construct the master controller asto combine chambers 109 and 111, or, without change inconstructlon,merely operate-jointly thevalves in pipes 112 and 114.

l I have now-described two embodiments of my invention as applied tofurnaces supplied with fuel from two different sources. In eachembodiment' of the invention the air supply to the furnace is dividedinto two parts each ma'ntained in predetermined relation with .one fuelsupply. In each embodiment the component air flows are combined into acommon stream prior to admittance to the furnace whereby, in the case ofregenerative furnaces of the type illustrated, a single regenerativepassage serves to preheat the total air supply and the total fuel andair said means, and means cooperating with said last supply may be mixedwith the total fuel supply at the burners within the furnace while stillinsuring the proper regulation of the air inproportion to the variousfuels. In each embodiment of the invention means are provided forreadily varying the conditions in the furnace chamber from oxidizing toreducing, and vice versa, while maintaining furnace operation at anydesired rating. .Although the invention is particularly adapted for usein connection with the control of open-hearth furnaces and has been soshown and described, certain features thereof may be advantageouslyemployed in the control of boiler, or other furnaces, particularly whensuch furnaces utilize a plurality of fuels.-

,I claim? 1. In combination with a reversing furnace burning a pluralityof fuels and provided with a pair of regenerative passages forpreheating the air upon reversal of thefurnace, a control systemcomprising a pluralityof air ducts equal in number to the number offuels burned inthe furnace and adapted to be connected in parallel witheach other and'in series with either of said passages, means forsupplying air to each of said ducts, a plurality of regulators oneassociated with each duct for controlling the flow ofairtherethrough, aplurality of fuel, supplying means, regulators for controlling thesupply of fuel fibm each of mentioned regulators and withsaid airflowregulators for maintaining a, predetermined ratio between the flow ofone of the fuels and the flow of air through one of said air ducts andbetween the flow of another one of said fuels and the'flow of airthrough another one of said ducts whereby when the total fuel supply isvaried predetermined ratios between each fuel flow and its coordinatedairflow are maintained.

2. In combination with an open hearth fur-' 4 rate of supply of thatfuel and for adjusting the regulators for the other component and forthe other fuel supply to maintain a predetermined relation between thelast mentioned component air flow and the rate of supply of the lastmentioned fuel. v

3. The combination according to. claim 2 wherein said master controllerincludes means for causing operation of all of said regulators to varythe total fuel and air supplies and for causing said regulators to varysaid ratios while maintaining the totalfuel supply constant. 1

4. In combination with a gas producer provided with fuel and airsupplying means and with a furnace supplied with gas produced in saidproducer and provided with additional fuel supplying means and air forburning the gas and additional connections to cause said regulators tomaintain a predetermined ratio between one of said component air flowsto the furnace and the air supplied to the producer and to maintain apredetermined ratio between the other of said component air flows to thefurnace and the rate of supply of said additional fuel to the furnace 5.The combination according to claim 4 wherein throw over valves areprovided in said connections at said master controller for readilyvarying said ratios from one valueto a second value whereby the furnaceatmosphere may be changed from oxidizing to reducing and vice versa.

6.. The combination according to claim 4 ineluding a regulator for thefuel supplying means for the producer connected to said mastercontroller for control thereby and a regulator for the pressure in saidfurnace independent of said master controller to maintain said pressureconstant irrespective of the furnace rating or of the ratio between thecomponent air flows and the respective rate's of fuel supply.

7. A control system for furnaces provided with fuel and air supplyingmeans and with regulators therefor comprising in combination a mastercontroller, and connections between said master 1 controller and saidregulators for transmitting control forces therethrough; said mastercontroller including means for independently and jointly adjusting thecontrol forces ,delivered through saidconnections and including throwover valves which in one position so control said connections as tocause delivery of one set of con-, trol forces to said regulators and inanother position so change said connections as to cause delivery ofanother set of control forces to said regubination means for supplyingthe air to the furnace in a plurality of component flows equal in numberto the number of different fuels to be burned, a regulator for each fuelsupply, a regulator for each of said component air flows, a mastercontroller provided with alternate connections to said regulators fordelivery of control forces thereto to control all of said regulators inunison to vary the furnace rating, and throw over valves at said mastercontroller controlling the alternate connections between said controllerand said regulators, said valves when thrown from one position toanother serving to change the connections between said regulators andsaid controller for delivery of difierent sets of control forces to saidregulators whereby when said valves are in one position one set ofratios between the fuel supplies and the individual component air flowsis maintained and when said valves are in another position a differentset of ratios between the fuel supplies and the component air flows ismaintained.

CHARLES H. SMOOT.

